Draft gear



May 3, 1966 K. G. EMPSON DRAFT GEAR Filed April 21, 1904 INVENTOR.KENNETH G. EMPSON WWJM ATTORNEYS United States Patent Filed Apr. 21,1964, Ser. No. 361,330 4 Claims. (Cl. 213-43) This invention relates toa railroad draft gear and more particularly relates to a combination ofrubber spring and hydraulic draft gear which will fit into the pocket ofthe yoke of a railroad car.

In my co-pending application, Serial No. 186,923 filed April 12, 1962, Idescribed and claimed a draft gear having two sets of rubber springswherein the draft and buff strokes could be individually varied.Although this is a highly advantageous structure, in many instances aless complex structure will suffice wherein a single set of rubbersprings serves both in buff and draft.

It is, therefore, an object of the present invention to provide a draftgear having a single rubber spring portion combined with a hydraulicportion.

Another object of this invention is to provide a draft gear havingrubber springs of high mechanical capacity so that the unit will notclose going either up or down a steep gradient.

A further object of the invention is to provide a draft gear having afast recovery after impact even though there may be considerablepressure on the unit.

Another object of this invention is to provide a combination ofhydraulic and rubber spring system in a railroad draft gear wherein thehydraulic system will absorb impacts and shocks and maintain controlover the rubber springs so that recoil is reducedto a fast, smoothreturn to the unstressed condition.

A further object of this invention is to provide a hydraulic draft gearhaving a relatively low hydraulic pressure due to its large piston areaso thatthe seals have a long life.

Other objects will be apparent'from the specification which follows.

The draft gear of the present invention is adapted to fit within thepocket of a railroad car sill wherein the pocket is defined by sidesills and forward and rear stops and wherein the draft rigging includesa yoke fitting around the draft gear. The back of the yoke rests on therear element of the draft gear and the yoke is connected to a couplerand the back end of the coupler bears against the front end of the draftgear. Thus, in draft, the yoke tends to compress the draft gear againstthe forward stops while in buif the rear of the coupler bears againstthe front end of the draft gear tending to compress it against the rearstops. Thus, the draft gear of the present invention tends to compressin either buff or draft and to assume an uncompressed form understationary conditions. It will be obvious from the description thatfollows that the draft gear of the present invention can be mounted inthe pocket in either direction. Thus, either of the cylinder end or therubber spring end can face outwardly when mounted on a railroad car.

In the drawings forming part of this application:

FIGURE 1 is a perspective view of a draft gear embodying the presentinvention.

FIGURE 2 is a sectional view of the draft gear shown in FIGURE 1.

FIGURE 3 is an enlarged view of that portion of the structure which isshown enclosed within the circle on FIGURE 2.

Turning now to a description of the drawing by reference characters, thedraft gear of the present invention has a cylinder 3 having a closed end5, the end5 having shoulders 7 and 9 extending beyond the cylinder 3 andhaving re-enforcing members 11. It will be understood 3,249,249 PatentedMay 3, 1966 that the end 5 with shoulders 7 and 9 is of such size as tofit within the pocket of a railroad draft gear.

The opposite end of the cylinder 3 is threaded into a cap 13 having aninner bushing 15 adapted to receive piston rod 17. Center plate 14 fitsaround the cap 13. A seal 19 provides an oil-tight sliding connectionbetween piston rod 17 and the bushing 15. A piston 21 fits in thecylinder 3 and is attached to the piston rod 17 by threads 23. Piston 21forms a loose fit in cylinder 3 so that hydraulic fluid can flow aroundthe edge of the piston. The piston 21 is provided with a passage 25 sothat oil from that portion of the cylinder which is designated 27 canenter the hollow stem of the piston rod 17. In the form illustrated, thepassage 25 is formed by a saw kerf, although it will be obvious that thepassage could be formed in other ways. The inner surface 29 of thehollow piston rod 17 forms a smooth cylinder and a free-floating piston31 is provided in this space. The piston 31 is provided with an oil seal33 and an air seal 35.

The opposite end of piston rod 17 is threaded into the second end plate37. Mounted between the end plate 37 and the center plate 14 are aplurality of rubber springs generally designated 39. These springs areof the general structure described in my co-pending application abovereferred to and comprise a series of metal plates 41 with rubber discsor rectangles 43 interposed between each pair of plates. Both the metalplates and the rubber springs have hollow centers and the piston rod 17fits loosely into the hollow centers.

The end 37 has an ear 3% on each side thereof in which studs 4%) arethreaded. The studs 40 pass through unthreaded holes in the plate 14 andhave nuts 42 at the endsthereof. Thus, the studs 40 on each side of thedraft gear hold the device in assembled relationship yet do notinterfere with the compression of the device.

The device shown in FIGURE 2 is in the unstressed condition wherein thepiston 21 is to the extreme right with the space 45 behind the piston aswell as the space 27 in front of the piston filled with oil or othersuitable hydraulic fluid. The hollow center of the hollow piston rod 17,designated 47, is filled with air or with an inert gas such as nitrogenand the chamber sealed by means of a plug 49. As pressure is broughtbetween the two ends 5 and 37 the rubber springs are compressed andsimultaneously the piston 17 carrying piston 21 moves to the left and,since the piston 21 forms a fairly loose fit in the cylinder 3, oilflows around its edges into the space 27. However, since the piston rod17 is of substantial size, compensating means must be provided for thechange in volume as the piston rod 17 moves into the space 45. This isaccomplished by means of the passage 25 which allows some of the oilwhich has flowed around the piston into the space designated 27 to flowinto the space in front of the floating piston 31. This drives thefloating piston 31 to the right compressing the gas in the space 47. Ineither buff or draft, the draft gear is compressed so that pressure isbuilt upon the springs 43, yet the action of the hydraulic fluid flowingaround the piston absorbs substantially all of the shock. When pressureis released, the rubber springs restore the parts to the positions shownin the drawings.

It is preferred that the opening leading from the piston to the centerof the hollow piston rod be located in that face of the piston which isattached to the rod, as illustrated. However, it will be obvious thatthe device would also be operative if the opening led from the oppositeface of the piston but thatin this event the opening must be of a verysmall size since it would be in parallel with flow around the edge ofthe piston.

Although a floating piston has been shown as the means for compensatingfor the change of volume within the e! cylinder as the piston rod goesinto the cylinder, it is obvious that other means can be used such asthe employment of a metal bellows or a flexible diaphragm.

I claim:

1. A draft gear for railroad draft rigging, said draft gear fitting withthe pocket of a railroad car comprising in combination:

(a) a first end plate;

(b) a second end plate;

(c) a hydraulic cylinder attached to the first end plate;

(d) a first piston in the hydraulic cylinder;

(e) a plurality of rub-her springs between the first and second endplates, said springs having hollow centers;

(f) a hollow piston rod attached to the first piston at one end thereofand attached to the second end plate at the other end thereof, saidpiston rod fitting with the hollow centers of the rubber springs;

(g) a hydraulic fluid in the hydraulic cylinder;

(h) a gas in the hollow piston rod;

(i) said first piston forming a loose fit in said hydraulic cylinderwhereby said hydraulic fluid can be caused to flow around the edges ofsaid cylinder;

(j) means whereby the hydraulic fluid can flow from the cylinder intothe hollow piston rod, thereby compressing the gas;

(k) and means for keeping the hydraulic fluid from mixing with the gas.

2. A draft gear for railroad draft rigging, said draft gear fitting withthe pocket of a railroad car comprising in combination:

'(a) a first end plate;

(b) a second end plate;

(c) a hydraulic cylinder attached to the first end plate;

(d) a first piston in the hydraulic cylinder;

(e) a plurality of rubber springs between the first and second endplates, said springs having hollow centers;

(f) a hollow piston-rod attached to the first piston at one end thereofand attached to the second end plate at the other end thereof, saidpiston rod fitting with the hollow centers of the rubbers springs;

(g) a hydraulicfluid in the hydraulic cylinder;

(h) a gas in the hollow piston rod;

(i) said first piston forming a loose fit in said hydraulic cylinderwhereby said hydraulic fluid can be caused to flow around the edges ofsaid cylinder;

(i) an opening on the side of said piston, said opening extending fromthe face of the piston into the hollow 4 center of said piston rod,whereby the hydraulic fluid can flow from the cylinder into the hollowpiston rod, thereby compressing the gas;

(k) and means for keeping the hydraulic fluid from mixing from the gas.

3. A draft gear for railroad draft rigging, said draft gear fitting withthe pocket of a railroad cam comprising in combination:

(a) a first end plate;

(b) a second end plate;

(c) a hydraulic cylinder attached to the first end plate;

(d) a first piston in the hydraulic cylinder;

(e) a plurality of rubber springs between the first and second endplates, said springs having hollow centers;

(f) a hollow piston rod attached to the first piston at one end thereofand attached to the second end plate at the other end thereof, saidpiston rod fitting with the hollow centers of the rubber springs;

(g) a hydraulicfluid in the hydraulic cylinder;

(h) a gas in the hollow piston rod; I

(i) said first piston forming a loose fit in said hydraulic cylinderwhereby said hydraulic fluid can be caused to flow around the edges ofsaid cylinder;

(j) a second piston in said hollow piston rod;

(k) means whereby the hydraulic fluid can flow from the cylinder intothe hollow piston rod, thereby compressing the gas;

(I) and means on said second piston for keeping the hydraulic fluid frommixing with the gas.

4. The structure/of claim 3 wherein the means for preventing thehydraulic fluid from mixing with the gas comprises an oil sealand an airseal.

References Cited by the Examiner UNITED STATES PATENTS 2,985,319 5/1961Simmons 2l343 3,031,089 4/1962 Spencer et a1 213-43 3,033,384 5/1962Zanow et al 21343 3,135,394 6/1964 Empson 213-43 3,150,866 9/1964Peterson Q 267-1 3,164,264 1/1965 Price et al 21343 ARTHUR L. LA POINT,Primary Examiner.

MILTON BUCHLER, Examiner. B. FAUST, Assistant Examiner.

1. A DRAFT GEAR FOR RAILROAD DRAFT RIGGING, SAID DRAFT GEAR FITTING WITHTHE POCKET OF A RAILROAD CAR COMPRISING IN COMBINATION: (A) FIRST ENDPLATE; (B) A SECOND END PLATE; (C) A HYDRAULIC CYLINDER ATTACHED TO THEFIRST END PLATE; (D) A FIRST PISTON IN THE HYDRAULIC CYLINDER; (E) APLURALITY OF RUBBER SPRINGS BETWEEN THE FIRST AND SECOND END PLATES,SAID SPRINGS HAVING HOLLOW CENTERS; (F) A HOLLOW PISTON ROD ATTACHED TOTHE FIRST PISTON AT ONE END THEREOF AND ATTACHED TO THE SECOND END PLATEAT THE OTHER END THEREOF, SAID PISTON ROD FITTING WITH THE HOLLOWCENTERS OF THE RUBBER SPRINGS; (G) A HYDRAULIC FLUID IN THE HYDRAULICCYLINDER; (H) A GAS IN THE HOLLOW PISTON ROD; (I) SAID FIRST PISTONFORMING A LOOSE FIT IN SAID HYDRAULIC CYLINDER WHEREBY SAID HYDRAULICFLUID CAN BE CAUSED TO FLOW AROUND THE EDGES OF SAID CYLINDER; (J) MEANSWHEREBY THE HYDRAULIC FLUID CAN FLOW FROM THE CYLINDER INTO THE HOLLOWPISTON ROD, THEREBY COMPRESSING THE GAS; (K) AND MEANS FOR KEEPING THEHYDRAULIC FLUID FROM MIXING WITH THE GAS.